The answer, broadly, is the chattering governments who need to say something, or been seen to be saying something, when tragedies like Christchurch happen. Christchurch wasn't Facebook's fault, any more than it was New Zealand's fault or Christchurch's fault.
But it is human nature - and especially political human nature - to lash out, react, look to blame, and preferably spread the blame. In our case it's security, gun laws and social media.
Don't get me wrong, social media has a lot to answer for. But it has a lot to answer for based on how it works - and how it works is a direct result of us. If there is no 'us', there is no social media. Social media and its freedoms are a reflection of who we are.
And tragically who we are at times is appalling. Social media, because it's global and not really regulated, sinks very quickly to the lowest common denominator. The brilliance of what it could be, through its freedom to connect and engage, is often forgotten by the reality of what it actually is.
So Ardern and Macron sitting around angsting will achieve nothing because when push comes to shove the Facebooks of this world will remain untouched.
Because one, the sort of reform they want is only achieved by global co-operation, which isn't happening and two, it's only achieved by us, the global population, agreeing and acting (which also isn't happening).
And three, the fundamental principles in which social media is founded, freedom of speech and expression, still, in most minds, outweighs the bad that comes with it.